The University of Southern California _ Pacific Rim Transdisciplinary Tobacco Use Research Center (USC-PR TTURC) will investigate the efficacy of tobacco and alcohol use prevention programs (1) across cultures, (2) within specific cultural contexts, and (3) dependent on individual-level variations for dispositional attributes. The previous USC TTURC projects focused on characterizing the role of culture in tobacco use behavior and prevention by investigating multiethnic and multicultural populations within the US and in China. The research indicated that cultural context and individual disposition have potentially important moderator effects on prevention prepares. The proposed USC-PR TTURC will extend this program of research with three projects and four cores. Project 1, Heritable and social-environment risks for substance use, will bridge the disciplines of psychology, sociology, and behavioral genetics to examine the genetic and social-environmental risk and protective factors for adolescent tobacco and alcohol use among adolescent twins in Southern California and Qingdao, China. Project 2, Effect moderation and mediation in prevention programs, will investigate specific social, behavioral, and programmatic characteristics that are associated with substance use outcomes following exposure to evidence-based prevention programs in the U.S. and Chinese youth. This investigation will determine not only the presence of main effects for variables in each domain but, significantly, the presence of interactive effects between children's personal and social characteristics and program characteristics in the prediction of prevention outcomes. Project 3, Genetic Variants and Tobacco Use in Chinese Adolescents, will investigate the hypothesis that genetic factors responsible for dispositional attributes, such as hostility and depression, may substantially influence both an individual's tobacco use progression and moderate the effectiveness of tobacco control intervention and prevention trials. The Measurement Core will assist TTURC projects by researching, developing, and validating measures to assess tobacco use and its psychosocial correlates. The Statistics Core will provide data management and statistical support for TTURC projects. The Career Development Core will provide a variety of training opportunities to support the development of the next generation of transdisciplinary scientists to advance our knowledge of the complex social, cultural, biological, and environmental determinants of tobacco use and alcohol comorbidity. The Administrative _ Scientific Liaison Core will provide the scientific and administrative leadership key to the efficient and productive operation of the Center. This transdisciplinary collab! oration will lead to a more complete understanding of the etiology of adolescent substance use across cultural contexts and across individuals, leading to the development of more effective prevention programs.